Bump yard from 0.9.19 to 0.9.20 (#89)

Bumps [yard](https://github.com/lsegal/yard) from 0.9.19 to 0.9.20.
- [Release notes](https://github.com/lsegal/yard/releases)
- [Changelog](https://github.com/lsegal/yard/blob/master/CHANGELOG.md)
- [Commits](https://github.com/lsegal/yard/compare/v0.9.19...v0.9.20)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Gemfile.lock

@@ -47,7 +47,7 @@ GEM
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.2)
     unicode-display_width (1.6.0)
-    yard (0.9.19)
+    yard (0.9.20)
 
 PLATFORMS
   ruby